#include <iostream>
#include <cstdio>
#include <cstring>
#include <set>
#include <map>
#include <stack>
#include <vector>
#include <string>
#include <queue>
#include <cstdlib>
#include <cmath>
#include <algorithm>
using namespace std;
typedef pair<int, int> pii;
typedef long long ull;
typedef long long ll;
typedef vector<int> vi;
#define xx first
#define yy second
#define rep(i, a, n) for (int i = a; i < n; i++)
#define sa(n) scanf("%d", &(n))
#define vep(c) for(decltype((c).begin()) it = (c).begin(); it != (c).end(); it++)
const int mod = int(1e9) + 7, INF = 0x3fffffff, maxn = 1e5 + 12;
char str[20];
char ans[20];
int len;
bool ok, key;

void dfs(int pos, bool limit, int four, int seven) {
    if (ok) return;
    if (four > len / 2) return;
    if (seven > len / 2) return;
    if (!limit) {
        rep (i, 0, len / 2 - four) ans[pos++] = '4';
        rep (i, 0, len / 2 - seven) ans[pos++] = '7';
        ok = true;
    }
    if (pos == len) {
        ok = true;
        return;
    }

    if (str[pos] < '4') {
        ans[pos] = '4';
        dfs(pos + 1, false, four + 1, seven);
    }
    if (ok) return;

    if (str[pos] == '4') {
        ans[pos] = '4';
        dfs(pos + 1, true, four + 1, seven);
    }
    if (ok) return;

    if (str[pos] < '7') {
        ans[pos] = '7';
        dfs(pos + 1, false, four, seven + 1);
    }
    if (ok) return;

    if (str[pos] == '7') {
        ans[pos] = '7';
        dfs(pos + 1, true, four, seven + 1);
    }
    if (ok) return;


}

int main(void)
{
#ifdef LOCAL
     freopen(“in.txt”, “r”, stdin);
     //freopen(“out.txt”, “w”, stdout);
#endif
     ll n; int T;
     sa(T);
     while (T--) {
        scanf("%s", str);
        len = strlen(str); ok = false; key = false;
        if (len % 2) {
            len++;
            rep (i, 0, len / 2) printf("4");
            rep (i, 0, len / 2) printf("7");
            puts("");
        } else {
            if (str[0] <= '3') {
                rep (i, 0, len / 2) printf("4");
                rep (i, 0, len / 2) printf("7");
                puts("");
            } else if (str[0] > '4' && str[0] <= '6') {
                printf("7");
                rep (i, 0, len / 2) printf("4");
                rep (i, 0, len / 2 - 1) printf("7");
                puts("");
            } else if (str[0] > '7') {
                len += 2;
                rep (i, 0, len / 2) printf("4");
                rep (i, 0, len / 2) printf("7");
                puts("");
            } else {
                dfs(0, true, 0, 0);
                if (key || !ok) {
                    len += 2;
                    rep (i, 0, len / 2) printf("4");
                    rep (i, 0, len / 2) printf("7");
                    puts("");
                } else {
                    ans[len] = '\0';
                    printf("%s\n", ans);
                }
            }
        }

     }
     return 0;
}